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Numbers k such that k and k+2 are both binary self numbers (A010061).
4

%I #8 Nov 29 2020 02:10:33

%S 4,13,21,30,37,46,54,78,86,95,102,111,119,128,133,142,150,159,166,175,

%T 183,207,215,224,231,240,248,270,278,287,294,303,311,335,343,352,359,

%U 368,376,385,390,399,407,416,423,432,440,464,472,481,488,497,505,526,534

%N Numbers k such that k and k+2 are both binary self numbers (A010061).

%C The least difference between consecutive binary self numbers is 2 (see Macris's proof at A010061).

%H Amiram Eldar, <a href="/A339216/b339216.txt">Table of n, a(n) for n = 1..10000</a>

%e 4 is a term since 4 and 6 = 4 + 2 are both binary self numbers.

%t s[n_] := n + DigitCount[n, 2, 1]; m = 550; c = Complement[Range[m], Array[s, m]]; d = Differences[c]; ind = Position[d, 2] // Flatten; c[[ind]]

%Y Cf. A010061.

%K nonn,base

%O 1,1

%A _Amiram Eldar_, Nov 27 2020